A 68-year-old woman is scheduled for total knee arthroplasty. Tranexamic acid is administered intravenously before tourniquet release. The primary mechanism by which this drug reduces perioperative blood loss is:

• A Direct inhibition of thrombin
• B Competitive inhibition of plasminogen binding to fibrin ✓
• C Stimulation of platelet aggregation
• D Activation of factor XIII

Explanation

Tranexamic acid is a synthetic antifibrinolytic that competitively inhibits the binding of plasminogen to fibrin, preventing its activation to plasmin and thus inhibiting fibrin clot breakdown. It does not directly inhibit thrombin, stimulate platelet aggregation, or activate factor XIII. In joint arthroplasty, it is administered intravenously or topically to reduce perioperative blood loss and transfusion requirements.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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